1. Field
The presently disclosed subject matter relates to a vehicle suspension system and a method of mounting a control arm of the suspension system to a vehicle frame. More particularly, the disclosed subject matter relates to a vehicle suspension system in which the control arm is attached by a fastening rod that extends from a cavity in the control arm and is connected via bushing to the vehicle frame. The rod can include a stopping structure configured to prevent the rod from passing completely through the cavity located on the control arm.
2. Brief Description of the Related Art
Typical vehicle suspension systems often require a great number of attachment mechanisms, and a great deal of space. The high number of components and their complex shapes also add cost and weight to a vehicle. In addition, the large volume required for these components also creates restrictions in vehicle design and also creates problems during repair in terms of added time required due to limited access to components, and added cost due to this added repair time and multiple part requirements. One area of concern is how each component is attached to the frame of a vehicle, particularly the suspension system components.
The vehicle suspension system connects the wheel mount structure with the vehicle frame. The suspension also controls a position of a tire with respect to the vehicle body for its ideal position during operation of the vehicle, and thus ensures optimal handling safety. It also prevents the wheel's axle/shaft from directly transmitting an impact or vibration from the road surface to the vehicle frame and in this way prevents damage of the vehicle cargo and improves the ride comfort for the vehicle passengers. Accordingly, the connection of the upper and lower portions of the vehicle's suspension system generally is made to be flexible to absorb the impact from the road surface, and to simultaneously moderate various forces applied to the vehicle's wheels.
Vehicle suspension systems typically include a complicated set of linkages, pneumatic devices, and springs that are designed to provide a smooth and relatively controlled ride for a vehicle. For example, a four bar linkage suspension can include lower and upper control arms connected on each side of the frame of a vehicle. The control arms are rotatably connected to the vehicle frame (e.g., by a “bar” type pivot/connecting device) so that they can rotate and move substantially vertically with respect to the vehicle frame. A knuckle typically connects each of the lower control arms to a respective upper control arm and a wheel mount structure can be attached to the knuckle. Thus, the wheel, when mounted, is permitted to move in a vertical direction relative to the vehicle frame.
The manner in which each of the components of a vehicle suspension system is connected to the frame of the vehicle and to each other has not typically been given a great deal of consideration other than to ensure proper functionality. For example, the control arms in a suspension system can be mounted in a variety of ways to the frame of a vehicle. The means of attachment can affect performance, safety, ease of serviceability and overall cost for a vehicle suspension system.
The control arms are specifically designed and positioned to allow the steering knuckles to move in a prescribed three-dimensional arc. Typically, the inner ends of the lower control arm have pressed-in bushings. Bolts, which pass through the bushings, serve to attach the lower arm to the vehicle frame. This is typically accomplished by pressing the bolt into the outer edge of the lower arm to simplify production of the parts. However, when an external force larger than a frictional force is applied to the bolt, the bolt can dislodge and retract from the same direction on the vehicle.
As shown in FIG. 5, a cross-sectional view of a conventional fastening mechanism can be provided where a fastener rod 25 is pressed in from the outer edge of a control arm 27 so that the fastener bolt shaft 28 is fed into the control arm cavity 29. This conventional fastening mechanism does not prevent the fastener bolt 25 from being dislodged and pulled out from the control arm 27. This method is typically used when the lower arm is made from a relatively lightweight material, such as aluminum, and it is thus necessary to use a bolt of relatively heavier weight material, such as steel, to connect to the bearing and vehicle frame. If the lower arm is made from a relatively heavy weight material, such as steel, a bolt may not even be necessarily used. For example, a rod like connection structure for connecting the lower control arm to the bushing and thus to the vehicle frame could be integrally formed with the steel lower control arm, or could be welded directly to the steel lower control arm.
Thus, other designs of mounting the lower arm exist wherein the fasteners are welded onto the arm or machined directly out of the arm material, integrating the arm and fastener into one piece. However, if the fastener is made from the same lightweight material as the lower arm, safety could be compromised, since the fastener undergoes a great deal of stress and is typically constructed from a relatively strong material. Typical mounting designs require heavyweight material for the connection between the lower control arm, bushing and vehicle frame.
Another example of a typical suspension system includes that disclosed in U.S. Pat. No. 5,938,220 (the '220 patent), which discloses a pivot bushing for a McPherson Type Suspension. The '220 patent describes a suspension arm of a three-point type. The suspension arm includes an outer anchoring point (for mounting of a lower bearing of a spring strut) and two inner anchoring points in the form of pivot means for pivotal mounting of the suspension arm to the vehicle body. The front pivot means is formed by a bushing extending essentially in the longitudinal direction of the vehicle and comprises a sleeve formed in the suspension arm. An elastic bushing element is inserted in the sleeve and is also shaped as a sleeve. The screw and bushing element and their guiding sleeve form an essentially conventional pivot means with the screw serving as a pivot axis.
There exists a need to provide a mount structure and method for mounting a lower control arm of a vehicle suspension system such that safety, cost-effectiveness, a ease of serviceability, are achieved.